A novel flex-rigid and soft-release ECoG array.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Electrocorticogram (ECoG) arrays are crucial for brain-computer interfaces and neurological research.
• Existing ECoG electrode designs face challenges in conforming to the brain's complex curvature and ensuring ease of handling during fabrication and implantation.
• The need for robust, adaptable, and easily implantable ECoG arrays is critical for advancing neuroprosthetics and epilepsy monitoring.

Purpose of the Study:

• To introduce a novel fabrication process for a high-density ECoG electrode array.
• To develop a free-standing, flexible ECoG array that conforms to the cerebral cortex.
• To optimize the handling, characterization, and implantation procedures for ECoG devices.

Main Methods:

• Fabrication of a multi-component ECoG array with distinct flexible recording and cable regions, and a rigid soldering area.
• Utilized polyimide films (5 μm thick) and gold electrodes (300 nm thick) for array construction.
• Designed a hexagonal measuring area (7.2 mm side length) for primary visual cortex implantation in Rhesus monkeys, incorporating OMNETICS connectors.

Main Results:

• Successfully fabricated a 128-channel ECoG electrode array with a flexible structure adaptable to cortical geometry.
• The free-standing membrane design with removable polyimide straps facilitated controlled soldering, characterization, sterilization, and soft release prior to implantation.
• Achieved a line resistance of 540 Ω from electrode site to connector pin.

Conclusions:

• The novel fabrication process yields a highly adaptable and user-friendly ECoG electrode array.
• This design enhances control during critical pre-implantation steps and ensures compatibility with the cerebral cortex.
• The developed ECoG array holds significant potential for advanced neurophysiological studies and clinical applications.